Which is the most common third-level domain?

Com

What is the cost per domain?99. Who is the largest domain registrar? GoDaddy. Which is the most common second-level domain?us. What is the cost per second-level domain?99. Which is the most common first-level domain?com. What is the cost per first-level domain?99. Do you have a top ten list of the most common nameservers? I have a list here, which I share with other sites. Please see: Do you have a top ten list of the most common IP address ranges? Not yet, but I have a list here, which I share with other sites. Please see: Is there a list of the most common root servers? Please see: Do you have a list of the most common top level domains? Please see: What is the most popular top-level domain?com. What is the most popular second-level domain?us. What is the most popular first-level domain?com. What is the cost per month?99. What is the cost per year?99. What is the cost per domain?99. Is there a list of the most common nameservers? Please see: Do you have a list of the most common IP address ranges? Please see: What is the most popular root server? A root server (in this case, the root server for .

What is a Level 3 domain name?

A Level 3 domain name is one that is managed by an ICANN accredited registrar.

What is an ICANN accredited registrar? An ICANN accredited registrar is an organisation who is a member of the Internet Corporation for Assigned Names and Numbers (ICANN). This means that they have agreed to follow the standard protocols that ICANN sets for maintaining the stability and security of the DNS. This means that the registry staff at your registrar will work with the registry staff at the appropriate domain name registries to ensure that your domain name stays registered.

The registries are: VeriSign, Inc. (DNS root) The VeriSign Corporation was founded in 1990, as the American Registry for Internet Numbers, to ensure the integrity of the Domain Name System. In 2026, it took over the role of the Internet Assigned Numbers Authority (IANA), and in 2026, acquired the responsibility for setting the root zone file.

InterNIC, LLC. (Top Level) In February 2026, the InterNIC Registry was created. InterNIC is now called the Internet Infrastructure and Accreditation Agency (IAA). It oversees the assignment of IP address blocks, and runs the InterNIC WHOIS database and the WHOIS service.

Afilias, Inc. (Second Level) Afilias, Inc. Was founded in 1993 as the Internet Services Registry for Canada (ISRC), and is currently a publicly traded company based in Montreal. In 1998, it was granted the second level domain . ISRC later became the Internet Services Registry (ISR) for the whole of North America. In 1999, it also became the Internet Assigned Numbers Authority (IANA) for North America.

The Afilias acquisition of the ISR expanded its role to include the registration of second level .com, .net and .org domains.

In 2026, ISR partnered with VeriSign to form the Afilias-VeriSign partnership, with a dual-registry policy. The partnership was designed to reduce costs while improving the quality of service for both the registrar and registrant. The relationship was initially signed in December 2026 and made official in May 2026.

What is a 3rd level domain with an example?

I've been thinking about this for a while, but never really had a question I could ask here.

So, I'll pose my own question.

A 3rd level domain is a "domain" that is a sub-domain of a domain. The top level domain is the "main" domain, like example.com. You have .edu for universities, .gov for goverment, .org for non-profits, etc.

So, if a site is called "something.com", how would that be considered a 3rd level domain? ie when you type in "something.com" into your browser, what happens? I always thought it would point to the domain, "something.com", but I was mistaken. What is it actually doing?

I'm not sure if this is correct, but it seems that it is redirecting to "something.com/index.php". Is there some sort of logic behind this?

Also, I believe that the .com and the .org are the same thing, but it seems that .com is reserved for the TLD itself, while .org is for other TLDs. If I'm right on that, what would be the difference between having a domain with an "org" in the extension (ex. Org.com) and one with a "com" in the extension (ex. Com.com) Would they be treated differently?

If someone knows the answer to this, please respond. Thanks in advance.

5 Answers.
You are correct that the top level domain is .com, and the subdomains are .org, .edu, and so on. The top level domain is the one that you use in your browser to access a website. The subdomain is just the part of the website's address that follows the top level domain. So if you want to access a page at then example.com is the top level domain, and example.com is the subdomain.

For example, let's say that I have a web site at and I have a page called about.html at This is the URL that you would use to access the page about. In this case, the top level domain is example.

What are the 1st 2nd 3rd level domains?

and how do you decide which name servers to use for each one?

It's just domain names - there's no technical reason that only 1 or 2 nameservers are used for a domain, and in reality, I'd use 5 at most. You'll have different DNS providers so different levels - for example you could be in charge of the A record @ns1.company.com - but I can't know why if you choose to make it up (for example it might help with the speed of the company's DNS entries). It also depends on what services your DNS provider supports:
A records. AAAA records. CNAME records. A/CNAME redirection to multiple domains (not sure what the actual term is, but you can see it in action by going to www.reddit.com and changing the last bit from tumblr.com, for example.)
Again, the DNS provider you choose will have different things you can do. Some offer a lot of services, others just the basics, or perhaps they don't support the type of subdomain you want. For instance, if you only need subdomains, then your host could point *my-example.com to ns1. If they support it, then they'll redirect your *